Cap and MrF appear together in 1 scene in the middle of SECWARS#6 visiting Beyonder to ask his intentions so they can't be split like this.

No-one else in FF#285, Av#262 or CA#313 cares where SECWARS#6 is. No-one else in SECWARS#6 cares where the other 3 are. So there is scope for adjusting something.

CA#313 has absolutely nothing to do with SECWARS.
Av#262 isn't labelled a tie-in but does mention trying to track Beyonder. It does says it's later than CA#312.

FF#285 is a genuine SECWARS tie-in. Beyonder visits Human Torch. But SECWARS#5 says it follows that, not SECWARS#6.
I can't find anything in the Forum or its archive which says that FF#285 has to follow SECWARS#6.
Beyonder's clothing in FF#285 isn't *identical* to either of the suits he wears in SECWARS#5-6, but I think it most resembles the version from #5 and the beginning of #6. He's changed into the new clothes before he meets Cap and MrF in #6.
One reason for putting FF#285 after SECWARS#6 may be that in SECWARS#6 MrF goes to ask Beyonder what he intends to do and Beyonder says he's still thinking about it, and in FF#285 MrF tells HT he doesn't know what Beyonder's purpose is. However I could read it the other way round - MrF doesn't know so he goes to ask.

On balance I'd follow SECWARS#5's claim and put FF#285 between #5 and #6. SECWARS#6 claims to be before CAD2#4, so for Beyonder SECWARS#6 will immediately follow FF#285.

There is a minor point about Beyonder's apps in SECWARS#5. It's actually 25 pages long rather than 23, and the last pages 23-25 contain the battle with the Avengers which you separate from the rest.

I would also suggest making the split between 22:3 and 22:4. Panels 22:4-22:7 don't actually include Beyonder so by your rules it doesn't matter where you split it for him. And no-one else needs to be split. But those panels have Boom-Boom ringing the Avengers to set the trap for him on the following pages. I would argue that those panels belong with the fight. And not only does the Beyonder have TG#30 and DS2#74 in the gap, but Dr Strange follows on with VIS&SCRW2#4 and DS2#75 before he joins in the closing pages of SECWARS#5. So I would argue against the Avengers waiting for all that to happen before executing Boom-Boom's plan, despite 22:4 having a 'Meanwhile' caption.

Or you could just list Beyonder as being in 1-22:3 and 23-25 and ignore 22:4-22:7 for him. After all it's not the job of the character chronologies to determine where panels only featuring other characters fit in the overall timeline. Unlike Paul's Calendar and to a lesser extent the timelines that Col_Fury's 'Recent chronologies: UTOPIA to SECRET WARS' thread points us to.